#include<stdio.h>
int main()
{
	int arr[] = { 1,2,3,4,5,4,3,2,1 };
	int len = sizeof(arr) / sizeof(arr[0]);
	int sum = 0,i = 0 ;
	for (i = 0; i < len; i++)
	{
		printf("%d ", arr[i]);
	}
	printf("\n");
	for (i = 0; i < len; i++)
	{
		sum ^= arr[i];
	}
	printf("%d", sum);
	return 0;
}